Non-interfering fire-alarm system



(No Model.)

M. G. CRANE. NON-INTERFBRING FIRE ALARM SYSTEM.

UNITED STATES PATENT OFFICE;

MOSES Gr. CRANE, OF NEWTON, MASSACHUSETTS.

NON-INTERFERING FIRE-ALARM SYSTEM.

SPECIFICATION formingpart of Letters Patent No. 253,847, dated February 21, 1882.

Application filed October 10,1881. (No model.) i

Newton, county of Middlesex, State of Massachusetts, have invented an Improvement in Non-Interferin g Fire-Alarm Systems, of which the following description, in connection with the accompanying drawings, is a specification.

My invention relates to a non-interfering fire-alarm system; and it consists mainly in a novel method of operation, having for its object greater security with the same expenditure of battery-power than is attained by the methods heretofore employed. 7

The apparatus used consists of fire-alarm signal-boxes to give the signals, a repeater whereby the signals sent from one box over one circuit are repeated over a number of circuits, and the usual signaling-instruments by which the signals are received, they consisting of bell-strikers, gongs, 8w.

The apparatus employed in carrying out my present invention may beprecisely the same,

except in one or two minute details, as that shown in Letters Patent, Nos. 223,218 and 223,248, granted to myself and Edwin Rogers, January 6, 1880, in which patents the said apparatus is fully illustrated and described, and will consequently need no further illustration here. The repeater described in the said patent No. 223,248 is adapted to reverse the direction of the electric currents employed while the signal is being given, and the boxes shown in Letters Patent N 0. 223,218 are rendered inoperative while the current is thus reverse from its normal polarity.

The present invention consists partly in reducing the strength of the currents employed while the signal is being given, and in such modifications in the construction of the repeater as to enable it to effect such reduction in the strength of the current, and in such modifications in the construction of the signalboxes as to render them inoperative while the strength of the current is thus reducedbelow its normal amount.

Figure 1 shows'in diagram one circuit of a non-interferin g system and a sufficient portion of the apparatus employed to illustrate, my invention; Fig. 2, a modification thereof, and Fig. 3 a detail to be referred to.

The signal-boxes, one of which is shown at A, may be precisely the same as the one shown in Letters Patent No. 223,218, with the exception of the electro-magnet a and its armature b, the latter being in this instance a neutral armature provided with a retracting-spring, c, and so arranged with relation to the poles of its magnet and its back-stop d that when retracted against the latter thesliding block d (the same as in the former patent) is removed from between the pull b and starting-lever O but when the said armature is attracted up to the pole of its magnet the said block is interposed between the said pull and starting-lever, the movements of the block at thus being the same as caused by a reversal of polarity of the magnet in the apparatus of the former patent. The armature b is so arranged that when retracted it is at a considerable distance from the poles of its magnet, so that it will require a much-stronger electric current to move it up to the said poles again than is required to retain it there. The armature b and its retra'ctor c are properly adjusted, so that the normal current derived from the battery 'B is sufficient to move the said armature with certainty from its retracted position up to the poles of the magnet, this being the current that is normally on the line 2.

When a signal is sounded from any box, as the one A, at the first break of the circuit the armatures b of all the boxes in the system, the circuits of which are all broken simultaneously by the repeater in the usualmanner, fall back to the position shown at A, Fig.

1, and the apparatus at the repeater, a part of which is shown in Fig. 1, at the same moment operates to reduce the strength of the current employed on the circuits, so that when they are again closed in the continuation of the signal the armatures b will not bemoved, butwill remain in the position shown in Fig. 1 until the end of the signal, thus rendering the pulls b of the boxes inoperative.

The electro-magnet M, by which the repeater is controlled, and the rheotrope-shaftc' and rheotrope lthereon, may all be operated in precisely the same manner and by the sameapparatus as shown in Letters Patent No. 223,248, the said shaft 1' being caused to turn half a ICO revolution at the first movement of a signal, and remaining in the inverted position until the signal is ended.

The rheotrope Z is somewhat different from the one shown in the former patent, which operates to reverse the direction of the current in the circuit when the shaft 6 is turned through half a revolution. In the present form there are three spring-fingers, 1 2 3, the former of which is connected with the binding-screw s and the extreme pole of the battery B. The spring 3 is connected with the binding-screw s and with an intermediate portion of the battery B, while the spring 2 is connected with one electrode of the repeater-magnet M, the other electrode of which is connected with the binding-screw s and the line containing the signal-boxes A, bell-strikers, and other instruments employed in a fire-alarm circuit, it being ultimately connected with the other pole of the battery B either directly or by an interposed ground.

The rheotrope Z consists of a metal connectin g-plate, Z mounted upon a cylinder upon the shaft 1', and of such shape that when the said shaft is in one position the springs 1 and2rest upon a continuous portion, 4, of the said plate and are electrically connected thereby; but when the said shaft 2' and connected cylinder and plate I have made a half-revolution the springs 2 and 3 rest upon and are electrically connected by the continuous portion 5 of the said plate, which is shown developed or flattened out in Fig. 3. When the springs 1 and 2 are thus connected the spring 3 rests on a plate, 1 insulated from the plate I, and when the springs 2 and 3 are connected the spring 1 is insulated therefrom, resting on the plate 1 In the normal condition the circuit passes from one extreme pole of the battery B to the hinding-screw s! and spring 1, thence by the portion 4 of the plate Z to the spring 2, and through the magnet of the repeater to the binding-screw 8 from which the circuit is continued through the various boxes and instruments to the other pole of the battery B.

Upon' the first operation of giving a signal the shaft t" is turned for half a revolution, as described in Letters Patent No. 223,248, and the circuit passes from the intermediate point of the battery to the binding-post s spring 3, portion 5 of the plate I, to the spring 2, and remainder of the circuit before described, that portion of the battery between the points connected with the springs s and 8 being thus removed and the strength of the current sufiiciently reduced to prevent the movement of the armatures b up to the poles of their magnets, although amply sufficient to operate all the necessary instruments in the circuit, they being constructed in accordance with the portion of the invention shown in Letters Patent No. 223,248, which is embodied in claims 1 and 2, or in accordance with the subsequent inventions upon which Letters Patent Nos. 242,511 and 242,512 were granted to me J uue 7, 1881, the said patents showing signalinginstruments adapted to be used in my present invention. The work usually performed by magnetism in apparatus of this class is in these inventions accomplished by amechanical motor, and the amount of magnetic force required is exceedingly small. When'the signal has been completed the shaft i is turned another half-revolution to its normal position, and the entire battery B included in the circuit, thus drawing up the armatures b and rendering the pulls b of the boxes again capable of operation.

The armatures b are adjusted to respond to a current of no greater strength than is commonly required to operate the apparatus usually employed in fire-alarm systems which do not contain the inventions for mechanically restoring the armatures to the poles of their magnets, and consequently by my present method I secure a much greater margin of safety with the same amount of battery-power than in any other system. The armatures b, when once moved up to the poles of the magnet, will be retained there by a very slight current, so that the effect of the battery B might become greatly impaired or the strength of the current greatly reduced below its normal amount, and yet the system be capable of giving a signal when required.

In a modification shown in Fig. 2 the strength of the current is reduced by interposing resistance instead of by removing a portion of the battery, the spring 3 being connected with the same pole of the battery as the spring 1, but having resistance-coils R interposed between it and the said pole of the battery.

I am aware that a non-interfering system has been previously invented, in which noninterference is effected by the removal of an armature in the signal-box beyond the range of attraction of its magnet at the first stroke of the signal; but in that system currents of the same strength are employed while a signal is being given as are normally upon the line, and the said armatures are restored to their magnets at the termination of the signal by an addition to the normal current thrown on momentarily for the purpose, thus necessitating the maintenance of an additional battery above what is required for the normal operation of the apparatus.

The signal-box shown in the application of Joseph W. Stover, filed June 9, 1881, is intended for operation in this system, the magnet or and armature b being arranged the same as shown in the present application; but the said armature, when retracted, instead of rendering the pulls b inoperative, engages another portion of the actuating-train, so that if the pull be operated and the stop-lever disengaged from the train while the armature is retracted the said train will be held by the secondary stop until the armature b is again attracted to the poles of the magnet. A portion of a box constructed on this plan is shown spring properly connected with the said genat A, Fig. 1. orator to receive a current of diminished 20 I claimstrength therefrom, and a circuit-terminal and 1. That improvement in the method of opera fire-alarm-telegraph circuit connected there- 5 ating afire-alarm-telegraph system for the purwith extending to the other pole of the said pose of producing non-interference of signals generator, and including signal-boxes with which consists in employing a-current of less controlling-magnets, to operate as described, 25 strength while a signal is being sounded than combined with a rheotrope-shaft operated by is normally used on the lines While no signals a repeater, and the rheotrope thereon co-oper- 10 are passing over them, and in producing the ating with the said circuit-terminals, in the said signals by opening and closing the said manner and for the purpose set forth. circuit while the reduced current is flowing, In testimony whereof I have signed my name 0 substantially as and for the purpose described. to this specification in the presence of two sub- 2. In a fire-alarm-telegraph system, a circuitscribing witnesses.

:5 terminal or contact-sprin g and a battery or MOSES .G. CRANE.

electric generator for producing a current of Witnesses: a certain strength, having one pole connected J 0s. P. LIVERMORE,

therewith, and a circuit-terminal or contact- W. H. SIGSTON. 

